An air filter of the generic type is known for example from DE 10 2013 014 488 A1. It has a filter housing which has a housing pot, a housing lid, a dirty-air inlet and a clean-air outlet. Arranged in the filter housing is a filter element which has an annular filter body, a first end plate at a first axial end of the filter body, and a second end plate at a second axial end of the filter body. Furthermore, the air filter is equipped with an inner shroud which is arranged in the filter housing, which is a separate component from the filter element and from the filter housing, and which has an annular grating body which is arranged coaxially inside the filter body. In the case of the known air filter, the inner shroud is configured as a supporting tube which is open at a first axial end of the inner shroud and is supported on the first end plate, which is configured as a closed end plate for this purpose. Via its second axial end, the inner shroud is secured to the housing pot in the case of the known air filter.
For a multiplicity of application cases, it may be necessary to rotate the filter element in the filter housing about the longitudinal center axis of the filter housing for installation and for removal. Such rotation may be necessary for example in order to activate or deactivate a lock between the filter element and filter housing. With the lock active, the filter element cannot be extracted from the housing pot. With the lock inactive, by contrast, the filter element can be extracted from the housing pot. Likewise, the lock is not active when the filter element is inserted into the housing pot. Such a lock can in this case expediently cooperate with the second end plate of the filter element, said second end plate leading when the filter element is introduced into the housing pot, i.e. faces a pot bottom of the housing pot. It is likewise possible for the housing lid to be placed on or removed from the housing pot by means of a rotary movement. Conceivable, for example, is a screw closure or a bayonet closure. In this case, the filter element can be rotated together with the housing lid. For example, it may be expedient to latch the housing lid to the first end plate in order to be able to ensure a predetermined rotary position between the filter element and housing lid. Furthermore, it may be conventional to attach a seal, for example in the form of an axial seal and/or in the form of a radial seal, to the second end plate. As soon as this seal is in contact with the housing pot during rotation of the filter element, high friction forces arise there, which counteract the rotary movement.
In the case of comparatively large filter elements, as are used for example in large utility vehicles, in particular in agricultural vehicles and in off-road vehicles, the axial spacing between the two end plates is comparatively large. Only very small torques can be transmitted via the filter body consisting of filter material. However, as soon as significant torque transmission between the two end plates is necessary for example for one of the abovementioned reasons, there is the risk of damage to the filter body. In order to avoid this, it is conventional to integrate the inner shroud into the filter element such that the inner shroud is firmly and permanently connected to the first end plate at its first axial end and is firmly and permanently connected to the second end plate at its second axial end. However, as a result, the filter element is comparatively expensive. Furthermore, there is a problem with regard to material separation when the filter elements are recycled, since the inner shroud is usually produced from a different material than the two end plates and the filter body.